package org.opentrafficsim.road.gtu.lane.tactical.lmrs;
   
   import org.opentrafficsim.base.parameters.ParameterException;
   import org.opentrafficsim.base.parameters.ParameterTypeDouble;
   import org.opentrafficsim.base.parameters.Parameters;
   import org.opentrafficsim.core.gtu.plan.operational.OperationalPlanException;
   import org.opentrafficsim.road.gtu.lane.perception.LanePerception;
   import org.opentrafficsim.road.gtu.lane.perception.RelativeLane;
   import org.opentrafficsim.road.gtu.lane.tactical.following.CarFollowingModel;
  import org.opentrafficsim.road.gtu.lane.tactical.util.lmrs.Desire;
  import org.opentrafficsim.road.gtu.lane.tactical.util.lmrs.LmrsParameters;
  import org.opentrafficsim.road.gtu.lane.tactical.util.lmrs.VoluntaryIncentive;
  
  /**
   * Determines lane change desire in order to adhere to keeping right or left. Such desire only exists if the route and speed
   * (considered within an anticipation distance) are not affected on the adjacent lane. The level of lane change desire is only
   * sufficient to overcome the lowest threshold for free lane changes.
   * <p>
   * Copyright (c) 2013-2018 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://opentrafficsim.org/docs/current/license.html">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision$, $LastChangedDate$, by $Author$, initial version Apr 13, 2016 <br>
   * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
   */
  public class IncentiveKeep implements VoluntaryIncentive
  {
      
      /** Free lane change threshold parameter type. */
      protected static final ParameterTypeDouble DFREE = LmrsParameters.DFREE;
  
      /** {@inheritDoc} */
      @Override
      public final Desire determineDesire(final Parameters parameters,
              final LanePerception perception, final CarFollowingModel carFollowingModel, final Desire mandatoryDesire,
              final Desire voluntaryDesire) throws ParameterException, OperationalPlanException
      {
          if (mandatoryDesire.getRight() < 0 || voluntaryDesire.getRight() < 0
                  || !perception.getLaneStructure().getExtendedCrossSection().contains(RelativeLane.RIGHT))
          {
              // no desire to go right if more dominant incentives provide a negative desire to go right
              return new Desire(0, 0);
          }
          // keep right with dFree
          return new Desire(0, parameters.getParameter(DFREE));
      }
  
      /** {@inheritDoc} */
      @Override
      public final String toString()
      {
          return "IncentiveKeep";
      }
  
  }